Densitometer sensors may be used for measuring the density of fluids. These fluids may be liquids, gases, mixtures of liquids and gases, and may also include small particles of suspended solids. Densitometers may be used in monitoring and/or controlling various industrial, manufacturing, or medical processes. Densitometers may also be deployed in oil and gas wellbores as a production logging instrumentation sensor, thereby allowing for a density measurement to be made at different depths within a wellbore. In wellbore applications, densitometer measurements may provide data that may be used to determine the type of fluid in or gas in the wellbore and may be used for water detection.
Due to the earth's geothermal temperature gradient, densitometers deployed in wellbore applications often operate at the high temperatures encountered as the depth of the wellbore increases. Additionally, the geothermal temperature gradient is not constant across the earth's surface and may be higher in some areas of exploration and production, as in the Haynesville region of the United States. Thus, deep wellbores in which it may be desirable to obtain densitometer measurements may have high temperatures in excess of 350° F. Traditionally, due to the limitations of existing transducer technology often utilized in densitometers, existing densitometers do not operate above 350° F. and are therefore limited in the wellbore depths or regions in which the densitometers may be deployed.
Quality, Q, of two-phase liquid-vapor mixture is a parameter that defines the proportion of a saturated vapor in the two-phase liquid-vapor mixture. One example of a two-phase liquid-vapor mixture may be steam. Given a mixture consisting of saturated liquid and saturated vapor phases, Q may be defined as the mass of the vapor, mvapor, divided by the total mass of the two phase mixture, mliquid+mvapor.
  Q  =            m      vapor                      m        liquid            +              m        vapor            With knowledge of the thermodynamic properties of a two-phase liquid-vapor mixture, Q may be combined with the corresponding temperature or pressure measurement of the two-phase liquid-vapor mixture to compute the amount of heat energy or enthalpy of the two-phase liquid-vapor mixture.
Q, combined with pressure and/or temperature measurements, has conventionally been used for monitoring and controlling various industrial and manufacturing processes including power generation.